Many of today's footwear products do not continually afford proper backpart fit of the shoe relative to the heel of the wearer's foot. This is particularly true for low-cut shoes having relatively long topline openings and inadequate means of adjusting the dimensions of those openings or the inside girth of the shoes. Examples of such conventional shoe styles include women's high heels pumps and flat or `skimmer` styles as well as casual slip-on designs such as loafers, espadrilles, and the like.
The problem of improper backpart fit stems from the tendency of shoes to stretch with wear, thereby allowing the foot to move forward in the shoe to such an extent that the heel loses contact with the back part of the shoe, resulting in looseness and slippage during use.
To date, the attempts to minimize this problem, which have been less than completely successful, have included back straps with elastic elements therein, counter and other insertable spacers or shims to tighten the fit, as well as the widely accepted but improper practice of fitting and selling shoes that are too snug girthwise and/or widthwise for the feet on which they are to be worn. Such fitting techniques often lead to serious consequences including foot discomfort and eventual health problems.
It is an object of the present invention to provide improved means to continually and gently urge a shoe continually forwards on the foot so that the backpart of the shoe will tend to stay in contact with the heel of the foot throughout the stride cycle and throughout the useful life of the shoe.
U.S. Pat. No. 4,575,954 (Bye) discloses a stretchable sock disposed within a shoe cavity. The purpose of the sock to provide additional support to the ankle of a foot inserted therein to inhibit lateral inward rolling of the ankle without unduly restricting foot flexion about the ankle joint in fore and aft directions. In addition, the sock is attached to the inside of the shoe to inhibit motion between the foot and shoe. Substantially constant pressure is, however, not exerted against the toes of the foot (other than would exist in any conventional sock) This is made clear in the specification at column 3, lines 3-4 wherein it is stated that stocking or sock is virtually non-elastic in the lengthwise direction. Rather, the Bye shoe system achieves stability by a totally different mechanism; the attachment of the sock to the interior of the shoe. Such a cumbersome sock system would not be suitable for use in a conventional shoe such as a woman's dress shoe, since it would extend out of the shoe to cover the ankle. This would result in an aesthetically displeasing shoe.
U.S. Pat. No. 2,440,563 (Woyach) discloses a removable protective lining for a storm boot. It contains no means for exerting a substantially constant pressure against the toes of a foot and nothing to urge a shoe forward on a foot to prevent heel slippage.
German Offen. 2,259,206 (Benner) discloses an insert for a child's ski-boot to change the length of the boot so that a too large boot may be used for a number of seasons. The insert has a dense outer surface to function as the normal relatively firm toe of a shoe. When a child's foot has grown to such an extent that the toes reach the insert, the insert is intended to be removed so that no substantially constant pressure is ever exerted against the toes. Accordingly, the insert can not continually urge a shoe forward on a foot.